Surgical cannulas are elongate hollow sleeves that are used to allow surgical instruments to be introduced through an animal body wall into a body cavity, preferably with minimal loss of body fluids and/or gases. Generally, in a first step of a surgical procedure a cannula is fitted with a stylet type trocar having a sharpened end and the assembly is pressed against the body such that the sharpened end of the stylet penetrates through the body wall. The cannula follows the sharpened end of the trocar through the opening with an exterior surface of the cannula sealing with the wall to resist loss of fluids. The sharpened stylet is generally removed and the interior channel of the cannula provides an entry passageway into the body cavity for the insertion of desired surgical instruments.
Often, when surgery is being performed using cannula means, a gas pressure is maintained in the targeted body cavity so that the body cavity is inflated to provide further room for surgical instruments to be conveniently manipulated within the body cavity. Thus, it is desirable that a cannula through which surgical instruments can be inserted into the body cavity, resists the passage of gases from the body cavity and/or is configured to allow the control of gaseous fluid to and/or from the body cavity.
It is known in the industry to use cannulas having trumpet valves incorporated therein. Trumpet valves generally clamp around the surgical instruments and must be manually manipulated during insertion and removal of the surgical instruments to maintain an adequate seal to prevent release of gas through the cannula. Trumpet valves can be difficult and cumbersome to manipulate and are generally seen by surgical personnel as inhibiting focused attention on the surgical procedure itself and as wearing or otherwise deteriorating costly insulated surgical trocar instruments.
It is also known in the industry to use cannulas having ball valves incorporated therein. Though ball valve assemblies are preferred by many in the industry to trumpet valve arrangements, the assemblies incorporating ball valve arrangements are generally seen as being difficult to sterilize for reuse, inconvenient for use with existing trocar instrumentation, cumbersome and generally also deteriorating to costly surgical trocar instrumentation.
It is an object of the present invention to provide an improved ball valve cannula arrangement which can be conveniently dissembled for sterilization and reuse.
It is another object of the invention to provide a ball valve cannula arrangement which can be operated in a way which does not significantly deteriorate surgical trocar instrumentation.
It is still a further object of the invention to provide a cannula ball valve arrangement which can be used with existing cannula.
It is still another object of the invention to provide a cannula ball valve arrangement having inexpensive disposable parts.
These and other objects of the invention will be apparent from the following recitation of the invention.